1. Field of the Invention
The present invention relates to a data transmission/reception system having a plurality of information transmitters/receivers connected to nodes on a bus, and adapted to transmit/receive data by establishing a connection between the nodes. More particularly, the present invention is directed to a technical field including a data transmission/reception system, a connection restoring method, and an information transmission/reception apparatus for executing connection restoration at the time of bus resetting on a serial bus compliant with Institute of Electrical and Electronic Engineers (IEEE) Std. 1394-1995 IEEE Standard for a High Performance serial Bus (IEEE 1394 Standard).
2. Description of the Related Art
In recent years, the IEEE 1394 Standard has attracted attention as a standard of an interface for transmitting digital data between AV devices or between computer peripheral devices. The IEEE 1394 Standard provides various advantages including capability of transmitting/receiving data at a high transmission/reception speed, a high degree of freedom for a topology connection, suitability for real time data transmission/reception carried out based on isochronous transmission/reception, and the like, and also provides higher usefulness compared with a conventional interface standard.
In consideration of general users' circumstances for a use, the IEEE 1394 Standard supports hot plug of a device with power ON. Therefore, bus resetting is generated when a topology connection of a bus is changed, and the connection established between the nodes is temporarily reset. However, data transmission/reception has been maintained for 1 sec after the bus resetting. Accordingly, it is necessary for each node to recover an original connection within 1 sec.
However, since a plurality of input plugs, and output plugs can be set in a device connected to each node on the bus of the IEEE 1394, there are also various types of connections, e.g., Broadcast-in connection, Broadcast-out connection, Point-to-point connection, and the like. Consequently, a connection restoration to be executed at the time of bus resetting become complicated. On the other hand, in each processing included in each connection restoration, for example, it is assumed that allocating of a channel or band may fail, or updating of registers of the input plugs and output plugs may fail. Therefore, in the case of keeping on performing each processing until it succeeds, since it takes much time to perform a specific connection restoration, there is a case where necessary time for the other connection restorations become short. As a result, there is possibility that one second after the bus resetting has elapsed while restorable connection is held unrestored, that is, there is possibility that a normal connection is prevented from recovering.